A bottom-feed fuel injector is one that comprises a fuel inlet port in its side a short distance above its nozzle, whereas a top-feed fuel injector comprises a fuel inlet port at its top end opposite its nozzle. A fuel rail assembly comprising bottom-feed fuel injectors comprises injector-receiving sockets that are open at both top and bottom ends. The open top end of a socket provides for a bottom-feed fuel injector to be inserted into and removed from the socket while the open bottom end allows the fuel injector nozzle to be placed in communication with an intake manifold runner that leads to an engine cylinder. The socket is shaped with shoulders for properly locating the fuel injector, and with the fuel injector properly seated in the socket, an upper O-ring seal that is disposed around the outside of the fuel injector above the fuel inlet port provides sealing contact with the socket wall to prevent fuel from leaking through the open top of the socket, and a lower O-ring seal that is disposed around the outside of the fuel injector below the inlet port provides sealing contact with the socket wall to prevent fuel leakage from the bottom of the socket. These two O-ring seals form top and bottom boundaries of a fuel zone of the socket that receives pressurized fuel through a main tube that serves fuel to a number of injector-containing sockets along its length. The fuel inlet port of each installed fuel injector is exposed to this fuel zone in its socket in order to receive pressurized fuel. The top of the fuel injector that is outside the socket contains an electrical connector that is connected to an electronic control unit that operates each fuel injector at the proper time. In order to secure each fuel injector in its socket, a retainer, typically in the form of a clip or bar, is releasably fastened to the fuel rail assembly so that only when it is unfastened can the fuel injector be removed.
When an engine-mounted fuel rail assembly is serviced, proper procedure calls for the entire assembly to be removed so that the fuel injectors, whether they be top-or bottom-feed, remain sealed to their sockets. If the proper procedure is not followed, such as by unseating or removing a fuel injector from its socket, resulting in loss of integrity of the bottom seal of a fuel injector to its socket, there is a risk that fuel in the assembly will drain by gravity out through the bottom of the affected socket. While escape of fuel in this manner is obviously undesirable, there is less likelihood of draining fuel intruding into an engine cylinder in the case of a fuel rail assembly that has top-feed fuel injectors in comparison to one having bottom-feed fuel injectors. This is because the nozzle ends of the top-feed fuel injectors will typically remain seated in the manifold runners if the fuel rail's sockets are separated from the tops of top-feed fuel injectors. Such will not be the case for bottom-feed fuel injectors. If the bottom seal is compromised while the fuel rail assembly is mounted on an engine, liquid fuel can immediately drain by gravity into the manifold runner, and if an intake valve to the corresponding engine cylinder is opened, the fuel may drain into the cylinder. A condition where a cylinder contains excess fuel is sometimes called "hydra-lock", and an attempt to start an engine with this condition may cause major engine damage.
The present invention relates to a means for minimizing, or possibly even eliminating, the possibility of hydra-locking an engine when the lower seal of a bottom-feed fuel injector is compromised while the fuel rail assembly is on an engine. Briefly, the invention contemplates the inclusion of a weir for damming the main fuel tube at each location where it communicates with a socket containing a bottom-feed fuel injector. The weir defines a level that fuel in the main fuel tube must overflow before it can flow into a socket. This level is neither so high nor is it so sized that it impedes the flow of fuel into a socket when pressurized fuel is delivered to the fuel rail assembly, but it is high enough that when the fuel is not pressurized, and the integrity of a lower fuel injector seal is compromised with the fuel rail assembly on the engine, at most only a minority of fuel, namely that which is above the weir level, has the potential to leak out of the fuel rail assembly, while a majority, namely that which is below the weir level, will not leak out. According to the disclosed embodiment of the invention, a weir level is created at each socket by making that portion of the socket's sidewall that intersects the main fuel tube fully imperforate except for a series of holes that allow the main fuel tube to communicate with the socket proximate the highest level of the main fuel tube. Thus, only fuel that is at or above that highest level has the potential to drain by gravity from the fuel rail since the dam created by the weir will prevent fuel at a lower level from draining out.
Principles of the invention will be seen in the ensuing description and claims that are accompanied by a drawing illustrating a presently preferred embodiment of the invention according to the best mode contemplated at this time for carrying out the invention.